Spacers for maintaining a predetermind spacing between the front and back plates of an evacuated flat panel display are known in the art. In a field emission display spacers provide voltage isolation between the display face, or anode structure, and the emitter assembly, or cathode structure; they also provide standoff of the mechanical forces of vacuum within the assembly. However, known prior art spacers suffer from a number of shortcomings. Some prior art spacers require elaborate fabrication steps or additional costly lithographic steps in the fabrication of the display. The additional spacer processing steps add to the cost and reduce yield. Other prior art spacers require attachment steps to affix the spacers to one of the plates of the display so that they will remain upright during subsequent packaging steps. These steps may introduce adhesive materials which outgas and thereby deleteriously affect the vacuum conditions in a field emission display. The additional attachment steps also significantly increase the fabrication time and cost of the display, since, often, each spacer must be attached individually. Bonding of spacers to the display plates is frequently performed at elevated temperature, thereby limiting the choice of spacer material to one which has a coefficient of thermal expansion substantially equaling the coefficient of thermal expansion of the display plate to which the spacers are attached. The requirement of a support structure to maintain upright spacer positioning during the final packaging steps, as well as an example of a field emission display and a packaging method for its fabrication (col. 8, line 34--col. 9, line 17), are taught in U.S. Pat. No. 5,448,131, to Taylor et al, which is incorporated herein by reference.
Other spacers that are known in the art have height-to-width ratios, or aspect ratios, which are inadequate for use in field emission displays, which require spacer aspect ratios of 2:1 or greater.
Accordingly, there exists a need for a spacer which overcomes at least some of the shortcomings of the prior art.